This invention relates to a motor/generator which has two rotors and a single stator.
Tokkai-Hei-11-275856 published by the Japanese Patent Office in 1999 discloses a synchronous motor/generator having two rotors and a single stator. Tokkai-Hei-11-275856 is a pre-examination publication of the Japanese patent application Tokugan-Hei-10-77449, the base of U.S. Pat. No. 6,049,152 that was issued after the priority date of this patent application.
A synchronous motor/generator disposes respective rotors superimposed co-axially in a radial direction on the outer and inner sides of a stator. Although the number of magnetic poles of the two rotors differs, the stator generates rotating magnetic fields by using one type of coil. The rotating magnetic fields consist of a rotating magnetic field which synchronizes the rotation of the inner rotor and a rotating magnetic field which synchronizes the rotation of the outer rotor. The inner and outer rotors are independently driven by applying a composite current to the single type of coil. The composite current comprises an alternating current generating the rotating magnetic field for the inner rotor and the alternating current generating the rotating magnetic field for the outer rotor. The stator comprises plate members laminated in an axial direction and is provided with a plurality of cores extending in a radial direction to allow wire to be wound thereon. When the motor/generator is assembled, the plate members are laminated and wire is wound onto each core.
In this motor/generator, leakage of magnetic flux which drives the inner rotor is defined by the magnetic resistance (hereafter termed xe2x80x9cinner magnetic resistancexe2x80x9d) between inner peripheral sections of cores situated between the inner rotor and the coil.
The leakage of magnetic flux which drives the outer rotor is defined by the magnetic resistance (hereafter termed xe2x80x9couter magnetic resistancexe2x80x9d) between outer peripheral sections of cores situated between the outer rotor and the coil.
Characteristics of the motion of the motor/generator vary on the basis of the ratio of the inner magnetic resistance and the outer magnetic resistance (hereafter termed xe2x80x9cmagnetic resistance ratioxe2x80x9d). For example, a power density, the power ratio of the inner rotor and the outer rotor or the ratio of the power source load factors of the inner rotor and the outer rotor varies on the basis of the magnetic resistance ratio. As a result, a desired magnetic resistance ratio differs depending on the required characteristics of the motor/generator.
However, in order to alter the magnetic resistance ratio, the design of the stator must be modified, so altering the magnetic resistance ratio during the manufacturing process of the motor/generator is difficult.
It is therefore an object of this invention to enable the magnetic resistance ratio of the stator to be set in an arbitrary manner during the manufacturing process of the motor/generator.
In order to achieve the above object, this invention provides a motor/generator comprising an inner rotor having a plurality of magnetic poles, an outer rotor having a plurality of magnetic poles which differs from the number of magnetic poles of the inner rotor, and a ring-shaped stator disposed between the inner rotor and the outer rotor. The stator is provided with a plurality of coils which simultaneously generate a magnetic field synchronized with the rotation of the inner rotor and a magnetic field synchronized with the rotation of the outer rotor. The stator is also provided with a plurality of cores on which the coils are wound. The cores are arranged in a circumferential direction and composed of a magnetic material. The cores have a connector magnetically connecting a part of a single core to a part of an adjacent core so as to set a magnetic resistance in a circumferential direction of an inner peripheral section of the cores located between the inner rotor and the coils and a magnetic resistance in a circumferential direction of an outer peripheral section of the cores located between the outer rotor and the coils.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.